There is a known bug were the installer does not correctly recognize your machine as an intel based machine when you are running in 64 bit mode. To install you will need to reboot in 32 bit mode (and then you can reboot into 64 bit mode after installation).

Subject: Re: This Installation will only work with Intel based Macintoshes.

There is a known bug were the installer does not correctly recognize your machine as an intel based machine when you are running in 64 bit mode. To install you will need to reboot in 32 bit mode (and then you can reboot into 64 bit mode after installation).